1. Field of the Invention
The present invention relates generally to motor vehicles, and in particular to audio systems for motor vehicles.
2. Description of Related Art
Most commercial motor vehicles include some form of audio system. The type and capabilities of the audio system vary widely. A basic audio system may as simple as an AM/FM radio and a loudspeaker. More sophisticated systems may include a cassette deck or compact disk (CD) player, and some also have the capability to play digital versatile disks (DVDs) and other video formats as well as audio.
As digital audio has become more popular, more motor vehicle audio systems have begun to include hard disk drives as audio sources. Alternatively, some motor vehicle audio systems provide a hard disk drive docking device with which the user can connect his or her own hard disk drive. The hard disk drives typically store digital audio files of the user's choice.
Physically, a hard disk drive comprises a stack of magnetic platters with a read head positioned over each platter. The distance between the read head and the platter may be only a few micrometers. For the sake of comparison, the diameter of a human hair is generally in the range of 80-100 micrometers.
All hard disk drives have environmental operating limits, extremes of pressure, temperature, humidity, and G-force beyond which the hard disk drive is not designed to operate. Operation beyond a hard disk drive's environmental operating limits may cause damage to the hard disk drive. As one example, increased or decreased atmospheric pressure may stress the read head mechanism, causing the heads to move downward and contact the platters, potentially damaging the platters and erasing the data stored on them. Alternatively, if the heads are moved too far away from the platters, they may no longer be within operating distance of the platters.
In their operation, motor vehicles are subject to a wide range of operating conditions. Although hard disk drives have become more common in motor vehicle audio systems, relatively little has been done to see that hard drives which operate in motor vehicles do not exceed their environmental operating limits.